While T-duality in supergravity involves dimensional reduction and so loses information, in the full quantum string theory the extra information is stored in string winding modes and so T-duality is a duality between the two 10-dimensional theories.
42.
A string theory with more gauge fields such as SU ( 2 ) gauge fields would then correspond to the compactification of some higher-dimensional theory above 11 dimensions, which is not thought to be possible to date.
43.
As he got to know the theory better, he saw that by re-introducing the 7th and 8th dimensions discarded from what had become Heim's 6-dimensional theory, two new forces could be derived which are related to normal gravity.
44.
Unlike the 10-dimensional theory, as was described in the previous subsection, the supergravity multiplet itself contains a vector and so there will always be at least a U ( 1 ) gauge symmetry, even in the N = 2 case.
45.
This new, dimensional theory meant that one could now attribute outcomes to ability ( an internal stable cause ), effort ( an internal unstable cause ), task difficulty ( an external stable cause ) or luck ( an external, unstable cause ).
46.
In the 1990s it was realized by Edward Witten ( building on previous insights by Michael Duff, Paul Townsend, and others ) that the limit of type IIA string theory in which the string coupling goes to infinity becomes a new 11-dimensional theory called M-theory.
47.
In 1995, at the annual conference of string theorists at the University of Southern California ( USC ), Edward Witten gave a speech on string theory that in essence united the five string theories that existed at the time, and giving birth to a new 11-dimensional theory called M-theory.
48.
3-dimensional Chern Simons action is equal to the instanton number, the 4-dimensional theory on M \ times S ^ 1 has a theta angle equal to the level of the Chern Simons theory, and so the 4-dimensional partition function is equal to-1 precisely when the instanton number is odd.
